(1) Field of the Invention
The present invention relates to an inking device for a printing machine, which a replacing work of a plate cylinder therein is made easier.
(2) Description of the Related Art
Heretofore, an inking device mounted on a printing machine, such as a rotary printing machine, is provided with an ink and a number of rollers. The ink, reserved in the ink fountain, is taken up by rotating the roller to adhere the ink to the surface of the roller in the state of an ink film. Subsequently, this ink film is uniformed and kneaded in various directions while transferred among a number of rollers, and then it is supplied to a plate surface on a plate cylinder by a form roller.
In such an inking device, there is a fear that a contact pressure between the form roller and the print surface, viz. a nip pressure is varied owing to the change in the diameter of the form roller by the thermal expansion and abrasion thereof, the finish state of the plate cylinder, and the like. Since the nip pressure largely influences the quality of prints, the nip pressure is adjusted in a printing preparation step or at the time of printing by providing the inking device with a nip pressure adjusting device. An example of this kind of nip pressure adjusting device is disclosed in Japanese Utility Model Publication No. 34670/1995 suggested by the applicant of the present invention.
Meanwhile, when an old number barrel is removed in order to replace the old number barrel (plate cylinder) with a new number barrel in a number printing machine, up to this time, a part (any form rollers etc. being situated in the direction of removing the number barrel to blockade the removal) of a plurality of form rollers that are rotatable is connect the plate cylinder had to be previously dismounted.
Accordingly, a man-hour for removing these rollers is increased, and moreover, it is required to adjust a nip pressure again, and hence it has caused a problem that a lot of hours and labor are necessary therefor.
An inking device presented by the applicant of the present invention is disclosed in Japanese Laid-Open Patent Publication No. SHO 63-172651. In this device, a plate cylinder etc. of which is able to be subjected to the maintenance service without a readjustment of a nip pressure by retracting a form roller largely from its operating position instead of removing.
This is, as illustrated in FIG. 7, under the condition that an ink supply unit 102 is dismounted, when a rubber barrel 100, pushing barrel 101, etc. are to be cleaned, and a spring 105 pushing a form roller 103 against a running-in roller 104 of the ink supply unit 102 is removed and the engagement between a claw 107 of a lever 106 and an engaging piece 108 of a frame is loosened, as shown by the imaginary lines in the figure. Thus, the form roller 103 and an ink holding roller 109 become shiftable largely along the periphery of a number cylinder 110 together with the lever 106, and thereby creating a space over the number cylinder 110 so that the cleaning work becomes easier.
However, in the above inking device, since it employs such a structure that the form roller 103, connected to the number cylinder 110 by the lever 105, is shifted along the periphery of the number cylinder 110 to retract from the operating position, there is a problem that the form roller 103, lever 106, etc. hinder the number cylinder 110 from being removed.
Accordingly, an object of the present invention is to provide an inking device for a printing machine, wherein a replacing work of a plate cylinder is easily practiced without dismounting a form roller or readjusting a nip pressure.